This invention relates to apparatus for reclaiming cellulosic fiber from scrap paper and the like.
Various types of apparatus have been used for reclaiming cellulosic fiber from scrap paper and the like (for which the term "pulper" is also used), among which is a pulper that produces pressure or shock waves in a liquid mixture to separate the cellulosic fibers. The latter type of pulper, also known as a "sonic pulper" because of the production of sonic or ultrasonic waves, is described in U.S. Pat. Nos. 3,323,733 and 3,420,454. Such a pulper is effective to defiber a paper sheet without mechanically shearing the cellulosic fibers, so that the fibers that are produced are longer and undamaged. ("Defiber" and "fiber" are terms used to describe the process of reducing cellulosic scrap materials, e.g., paper, into cellulosic fibers.) Moreover, the debris, such as plastic film, that customarily accompanies the scrap paper in municipal waste to be recycled is more readily segregated and removed from the paper fiber by a mechanical filter, for the plastic tends not to be sheared or otherwise broken down. Such pulpers have been found to be very effective in reclaiming cellulosic fibers from waste paper.